I think ssh is "draining" the input stream, which in this case means the pipeline coming into the while loop. Try redirecting the ssh input stream from /dev/null:

  /usr/bin/ssh bwadmin@${MACHINE} "hostname" < /dev/null

I tested that with this command line:

 ls | while read a; do ssh 192.168.1.4 hostname < /dev/null ; done

and got back the remote host name once for each file in the local directory.

Ralph Mitchell

On Thu, Dec 15, 2011 at 4:01 PM, oliver <ohemming at gmail.com> wrote:

I have 6 servers in my hosts.cfg file that use a custom script with a HOSTTAG of cdr

The script is located at $XYMONHOME/ext/check_cdr.sh

If I make it as basic as possible, it all runs perfectly. For example:

================================ #!/bin/bash -x

HOSTTAG=cdr COLUMN=$HOSTTAG

$XYMONHOME/bin/xymongrep $HOSTTAG | while read L do set $L # To get one line of output from xymongrep HOSTIP="$1" MACHINEDOTS="$2" MACHINE=echo $2 | $SED -e's/\./,/g' COLOR=green MSG="running on ${MACHINE}" $XYMON $XYMSRV "status $MACHINE.$COLUMN $COLOR date ${MSG} " done

exit 0

I realise the test itself is useless, it's just to demonstrate the problem.

Since I have the -x on the first line, I see it iterate through all 6 servers in the log file I specified in the tasks.cfg file

This is part of the output, going from the first server to the second

• /apps/xymon/server/bin/xymongrep cdr
• read L
• set 10.64.91.99 as1wdc1 '#' cdr
• HOSTIP=10.64.91.99
• MACHINEDOTS=as1wdc1 ++ echo as1wdc1 ++ /usr/bin/sed '-es/\./,/g'
• MACHINE=as1wdc1
• COLOR=green
• MSG='running on as1wdc1' ++ date
• /apps/xymon/server/bin/xymon 127.0.0.1 'status as1wdc1.cdr green Thu Dec 15 20:57:41 GMT 2011 running on as1wdc1 '
• read L
• set 10.64.123.67 as2dal1 '#' cdr
• HOSTIP=10.64.123.67
• MACHINEDOTS=as2dal1

But if I add the following line to the script, directly above the "$XYMON $XYSERVER... " one, I only see the first server get queried before the script exits and ultimately, my other 5 servers go purple.

/usr/bin/ssh bwadmin@${MACHINE} "hostname"

With the ssh line, my last bit of output in the log file is:

• /usr/bin/ssh bwadmin at as1wdc1 hostname AS1WDC1 ++ date
• /apps/xymon/server/bin/xymon 127.0.0.1 'status as1wdc1.cdr green Thu Dec 15 20 :52:37 GMT 2011 running on as1wdc1 '
• read L
• exit 0

What is it about the ssh command that causes the "while read L" loop to fail?

Thanks

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